Thermal switch



Feb. 16 1926.

O; A. COLBY THERMAL SWITQH Filed May 10, 1922 all of the main portion of the tube.

coil may ,be mountedon one Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE."

ORA A. COL BY, OF IRWIN, PENNSYLVANIA, ASSIGNOR' TO WESTINGHOUSE ELECTRIC 8c MANUFACTURING COMPANY, A CORPORATION .OF PENNSYLVANIA.

THERMAL swrr'cn.

Application filed May 10, 1922. Serial No. 559,724.

T; all whom it may concern:

Beit known that I, ORA A. COLBY, a citizen of the Unitedr States, and a resident of Irwin, in the county of Westmoreland and] State of Pennsylvania, have invented a, new and useful /Improvement in Thermal Switches of which the following is a specification.

My invention relates to circuit interrupters and particularly to fluid circuit interrupters and it has for its object to provide a relatively simple and rugged circuit-interrupting device that shall be eifective to-interrupt an electric circuit either manually or automatically.

In practising my invention, I provide a closed evacuated tube of insulating material having a main portion of substantially U-shape and an integral lateral extension connected to the main portion at one end thereof. Electric circuit terminals extend into the-main portion of the tube, at the ends thereof, and operdtively engage a column of conducting fluid which fills substantially An auxiliary heating portion adjacent the end thereof to aid in volatilizing the conducting fluid at that point and thereby cause the circuit through the device to be interrupted. The be mounted in a support having a turning movement to permit of, manually interrupt- 'ing the circuit or of reclosing the circuit after it has beeninterrupted either automatically or manually. I I

In the single sheet'of the drawing, Figure 1 is a diagrammatic representation of an electrical y heated device with which is associated a fluid circuitdnterrupt ing means embodying my invention;

Fig. 2 is a View, in side elevation, of a device embodying my invention;

Figs. 3 and 4 are end and top plan views, respectively, of the device illustrated in Fig. 2; i i

Fig. 5 is a view, in side elevation, of a modification of the device embodying my invention; and

Fig fi is a view, in slde elevation, of a tube may it the temperature ot the heated device,

device embodying my invention in a suitable mounting means.

Referring more particularly to Figs. 2, 3 and 4, a fluid circuit interrupter comprises a closed evacuated tube 11 of any suitable.

insulating material, such as glass or quartz,

and bent to substantially U-shape. At each of the ends of the tubes there is provided an electric circuit terminal v12 which extends through the wall of the tube at the end thereof, and operatively engages a column 13 of "a suitable conducting fluid, such as mercury. The tube also comprises an integral lateral tubular extension 14 connected to the main portion of U-shape at one ofits ends andextending laterally and downwardly therefrom. The device is intended to be mounted in substantially the position illustrated in Fig. 2 of the drawing; that is, the connecting or intermediate portidn of the tube is at the bottom.

Fig. vl illustrates, diagrammatically, the device operatively associated with an electrically heated apparatus 15, represented generally as a rectangle, and here intended to represent a furnace or=any other electrically heated apparatus. A resistance or heating element 16 is associated with the device 15 and the circuit-interrupting device is so located relatively to the electrically heated device that one end thereof, namely, that 0pposite to the one at which the lateral extension is located, is under the thermal influence of the electrically heated device. If desired, or necessary, the circuit-interrupting device may be so located as to extend partly into the electrically heated device to obtain a more direct transmission of heat from the electrically heated device to the circuit inter'rupter.

It the heating'element 16 is energized and device reaches a predetermined maximum value, a part of the conductin thermally i uenced by the electrically is volatilized and causes a portion oi the conducting fluid located in the other end of the tube adjacent-the lateral exteneion to be forced out of the tube fluid in that end of the tube,

of substantially U -shage and into the lateral wh extension. to be trappe there and prevented from returning. It is evident that when a sufficient amount of the conducting fluid is forced o 'er into the lateral extension, the circipit through the device is interrupted.

the temperature of the electrically heated device-is not sufficientlyhigh to cause volatilization of the proper amount of the conducting fluid in one of the legs of the tubular member of U-shape, an auxiliary heating coil 17 may be operatively associated 'th that leg of the tubular member to geneyate additional heat and to effect a quicker volatilization of the conducting fluid and a quicker interruptionof the circuit therethrough. If desired, the ,diameter or the area ofthe cross-section of the column of conducting fluid may be made relatively small at that end of the tube which is to be thermally influenced by the electrically heated device to generate additional heat internally of the circuit-interrupting device and cause the circuit to be interrupted sooner than would be the case if only externally applied heat from the electrically heated device were available to cause the operation of the circuit-interrupting device.

Referring more particularly to Fig, 6, I have there illustrated a suggested form of mounting of the device embodying my invention to permit of either manually interrupting the circuit br of reclosing the cir- .members 19 and .ton or handle 25 may be in either of this forms cuit after it has been automatically opened,

as hereinbefore described. A suitable base member 18is provided with bearing memb'ers 19 and 21 which may be integral therewith or secured thereto and which carry a supporting and clamping member 22 of such form as to co-operate with, and properly support, the tubular member of U-shape and its integral lateral extension, in proper operative 'position. Short integral shaft extensions' 23 and 24 may be provided on the.

member 22 to be mounted in the bearing 21, and an operating butsecured at the outer end of the shaft extension 24 to permit of manually operating the mechanism. I have illustrated a pair of integral clamping extensions or lugs 26 adapted to extend around the middle portion of the tubutar. member of U -shape to properlysupportnand hold the same, course, that any suitable or desired mechanism may be employed and further differences in design be efiected to hold the tube its limiting positions, although no part of my invention and is not therefore further described.

f it .is desired to interrupt the circuit manually,.the tube. may

be given a turning movement 1n"1ts su por 111 a clockwise d1rec-' It is to be understood, bf.

flows into the integral'lateral extension 14: and is trapped there, causing the conducting fluid to be disengagedfrom either or both of the electric-circuit terminal members 12. If it is desired. to again close the circuit, this may be done by moving the tube in a counter-clockwise direction sufficiently to cause the conducting fluid to again flow into the main portion of the tube, substantially as illustrated in Fig. 2 of the drawing, [I1 operation which must be performed not yflly after the circuit has been manually interrupted but also when it has been automatically.interrupted, as hereinbefore described.

The device embodying my invention thus provides a relatively simple, compact and rugged construction of fluid circuit interrupter which is effective to either manually or thermally interrupt the circuit through an electrically heated device with which it is operatively associated or it may be employed to manually interrupt a circuit through an electrically heated apparatus which does not thermally influence the circuit interrupting device. If the temperature of the electrically heated device is not sufficiently high to cause proper automatic operation of the device, a small auxiliary heater may be added to cause operation of the device under a predetermined set of temperature and current conditions.

Various modifications may be made in the device embodying my invention Without de-' parting from the spirit and scope thereof and I desire that only such limitations shall be placed thereon as are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. In a fluid circuit. electrically heated device, in combination, a closed, evacuated tube of insulating material having a main portion of substantially U-shape and an integral lateral extension connected to one end of said main portion, electric circuit terminals extending into said tube at the ends of the main portion, a conducting fluid filling substantially all of said main portion, and an auxiliary electric heating means connected in seriescircuit relation to .said circuit interrupter and surroundin an endportion thereof to cause vaporization of the conducting fluid in said end portion by heat generated thereby when added to thatof the electrically heated device thermally influencing said end portion surrounded by the auxiliary heating means, to thereby interrupt the circuit.

2. In a fluid circuit interrupter for an electrically heated device, in combination, a closed evacuated tube of insulating material of substantially U-shape supported in a substantially upright position, electric circuit interrupter for an ereby a portion of the conducting fluid terminals extending into said tube at the ends thereof, a conducting fluid in said tube substantially filling the same, one end of said tube being thermally influenced by the electrically heated device with which it is operatively associated to va orize a portion of the conducting fluid int at end of the tube to cause another part of the fluid to be forced out of said tube, and a tubular member integral with said tube of U-shape and ex- 1 tending laterall and downwardly therefrom at one en thereof for receiving and trapping said fluid forced out, of said tube. In testimony whereof, I have hereunto subscribed my name this 28th day of April 15 ORA A. COLBY. 

